Complications of Alloplastic Graft Materials Used in Cranioplasty: Systematic Review and Network Meta-Analysis

BACKGROUND Autologous bone grafts are commonly associated with higher complication rates than alloplastic materials in cranioplasty. While previous systematic reviews have shown favorable outcomes with alloplastic grafts, there is limited comparative data on the performance of different alloplastic materials. This systematic review and network meta-analysis aims to assess the efficacy of alloplastic materials used in cranioplasty, focusing on complications, re-surgery, and implant exposure. MATERIAL AND METHODS Following PRISMA and PRISMA for network meta-analyses (NMA), we searched PubMed/MEDLINE, Embase, Scopus, and Web of Science (January 2015-January 2025). Eligibility criteria were adult cranioplasty cohorts comparing 2 or more alloplastic materials and reporting at least 1 pre-specified outcome: infection, overall complications, implant exposure, or re-surgery. Data extracted a priori included study design, indication, implant material (polyetheretherketone, titanium, hydroxyapatite, polymethylmethacrylate [porous and hard], ultra-high-molecular-weight polyethylene), follow-up, and event counts per outcome. Random-effects models estimated pooled effects; NMA generated P-scores/SUCRA ranks. Heterogeneity (I²), transitivity, and incoherence were assessed. Risk of bias was measured with the Newcastle-Ottawa Scale. RESULTS From 1025 studies, 24 studies met the inclusion criteria. The highest complication rates were reported for polymethylmethacrylate, hydroxyapatite, and titanium, although differences were not statistically significant. SUCRA rankings suggested the lowest infection rates with polyetheretherketone and titanium. Meta-regression indicated that polymethylmethacrylate was associated with higher incidence of infection. Network analysis showed titanium had maximum implant exposure. Polymethylmethacrylate (P-score=0.79) and hydroxyapatite (P-score=0.73) carried the highest re-surgery risks. CONCLUSIONS Polymethylmethacrylate and hydroxyapatite were associated with higher infection and re-surgery rates, while titanium showed greater implant exposure.